Tyre pressure/tps reading

[tapps]

I checked the tyre pressures on my gtr,whilst cold.ie prior to use,they were both low in pressure,I used two types of gauges.topped up to 42psi front & rear.when I was on my way I went through the options on the screen,it was reading 47psi front & rear.i pulled over & let a little air out,I know when the tyres warm up the psi increases.Which gauge would you go by.the gauges i used were a digital one & a dial one.i let the bike stand for an hour & set the front & rear at 41psi.

[Burchy]

Stick to the proper guages.  The handbook says not to rely on the TPS and only use it as a guide

[Lonewolf]

Funnily enough mine did exactly the same today. A few days ago when it was quite cold I inflated my tyres to 43psi. I always do them 1psi over to allow for any loss of air taking the adapter off the valve. I only did a short distance today but as soon as I set off they were redaing 45psi and once I got onto a dual carriageway and sped up they were reading 46/47psi. Far too high is that.
I'm sure Asif did a tyre pressure guide depending on ambient temperature as to what you should inflate to, or am I dreaming? Either way if you inflate when its extremely cold expect your running pressures to be excessive. 

[SirToU]

Hi

I don't think the GTR suffers with tyre pressures that much, however.

I have three guages - a cheap dia guage, an expensive dial gauge and a digital tyre guage.

if I used either of the dial guages, the TPS always reads +1/+2 psi high on the TPS.  However if I use the digital (freebee from fastbikes mag), It is spot on, so I use this when the tyres are cold.
If set on the low side of 42 (guesswork and experience - digital guage is also 0.5psi)  the pressure stays pretty much correct all the time.

however, a couple of days later, I will loose 1-2psi, but nothing I'm too concerned about.

however, given all that, I run the Z750R at about 30-32psi - manufacturers recommends 36F 42R....  But I would like to think I know what I'm doing!  :-)

Neil

[viper]

i remember asifs tyre chart and noted that the changes in tyre pressure with ambient pressures to be pretty much on the mark.

when the handbook says check tyre pressure when cold they are referring to the tyre and not a freezing cold day . if its only 5 degrees outside then you will see an increase in 4 or so degrees when they warm up

last year i set my tyre pressures at at approx 18 degrees to 42 psi before i set off to europe and  even in Italy when it was 35 dgress never saw the psi rise above 44

[Deon]

In my experience, the dash readings are always a bit higher than what the pressure actually is. What is more important for me is that the dash will indicate when you have a tyre that is low on pressure. It works ( as I found out recently ) and that is what I think the benefit is of the dash readout.

Deon

[O.C.]

In my experience, the dash readings are always a bit higher than what the pressure actually is. What is more important for me is that the dash will indicate when you have a tyre that is low on pressure. It works ( as I found out recently ) and that is what I think the benefit is of the dash readout.

Deon

use the dash reading as a guide only, I have a couple of gauges and TBH they all vary slightly, I like my tyres set at 42psi cold, they will inevitably warm up when the bike is on the move 

[trousersnake01]

I use a calibrated air gauge at work to 42 and the bike always shows 46/47

[Teacher]

P1xV1/T1=P2xV2/T2  where P = pressure  , V = volume and T = temperature in Kelvin,

So assuming the volume stays the same, or approximately the same, as it is dictated by the volume of the tyre carcass, then P1/T1=P2/T2

So if P1= 41psi, and T1 = 4 degrees centigrade or 277 K

then at 20 degrees centigrade or 293 K we have P2=( 41/277) x 293 =43 psi

So if you adjust your tyre pressure to 41psi at 4 centigrade, it will rise to 44 psi at 20 centigrade

Unavoidable, ladies and gents, it's combination of Boyles law and Charles' Law. Simple physics

[pistole]

- aiyayayaya !



.

[Deon]

Just an interesting observation that some of you might find usefull. I was at a rally and the dash showed rear tyre low pressure warning  ( 2.2 Bar ) - about 32 PSI. Not near a garage to inflate tyre so got out the puncture repair kit with the Co2 cannisters in. Instruction leaflet states that 1 cannister will inflate tyre to 3 Bar ( about 43 PSI ). Well, too cut a long story short, it took 2.5 cannisters to get my tyre to 2.8 Bar (41 PSI ) from 2.2 Bar.
As the kit only contains 3 cannisters, I was fortunate that it got me home OK. However, I have now bought 6 cannisters that I have put in the repair kit. If I had no pressure in the tyre to start with, 3 cannisters would not have been enough to inflate the tyre.
Useless info but might just make you go out and get some more cannisters in your kit !!

Deon

[routemaster]

A few years ago I had the same issues with CO2 cannisters when I had the CBF1000. Puncture in rear tyre, which was then sealed and I tried inflating the tyre with C02 cannisters, it took 3 of them to get any where near a pressure I could ride to a garage to inflate the tyre properly.

These days I carry around a small tyre pump compressor in the pannier, which has come in hand a couple of times when friends have had punctures when out on a ride or on a tour.

Steve

[pistole]

- the experience of the above two gentlemen is the reason why i don't ever rely on CO2 canisters. Imagine being able to patch but not able to inflate the tyre ....

- a small electric pump (and a backup mini bicycle pump for long trips) is gold.

.

[KeVstrom]

While were on the subject of tps's, how much do the sensors cost to replace?

[Burchy]

About £165 each before fitting costs